Solar heat collection system

ABSTRACT

A solar heat collection system for heating water, the system comprising in one embodiment a plurality of lengths of water conduit pipe inside lengths of water conduit jacket pipe and spaced apart therefrom, with an insulating medium contained between the pipe and jacket pipe. The lengths of water conduit pipe are fluidly connected together to provide a circulation system for the water such that solar heat energy may be provided to a heat load. A variety of connection methods for connecting the lengths of piping are provided and the lengths of piping may be flexible for a variety of solar heat system installations.

FIELD OF INVENTION

The invention relates to improvements in a solar heat collection system which in a typical embodiment is a solar water heating system.

BACKGROUND

A solar heat collection system such as a solar water heating system typically comprises one or more heat collecting elements through which a working fluid such as water is circulated and is heated. The solar heat collecting elements are commonly mounted on a roof, a wall, or other location which will expose them to the sun. In a domestic or agricultural or commercial or light industrial application such a solar heat collection system is typically used to heat water, or assist in heating water, or for space heating, for example.

A solar heating system also includes conduits to conduct the working fluid from the one or more heat collecting elements, through for example the roof and/or walls of the dwelling or building to which the heat collecting elements are mounted, to a hot water cylinder for example or other heat load.

Commonly the conduit used is copper or plastic pipe, and the pipe is lagged with an insulating material to reduce heat loss.

In the great majority of such solar water heaters in current use, the heat collection elements are incorporated into one or more large flat rectangular elements. These typically comprise solar tubes mounted on a purpose-built manifold.

There are several disadvantages to this system. Firstly, a significant amount of heat is lost from the system and, in particular, the piping connecting elements of the system together. Secondly, the relatively large size of the rectangular collection elements can cause difficulties with mounting them and it also engenders a lack of flexibility in designing and installing the solar heat collection system. Thirdly, the relative complexity of the rectangular collection elements adds expense to solar water installations and may make the collection elements themselves difficult to modify or repair.

It is an object of the invention to provide an improved or at least alternative form of solar heat collection system and/or conduit system for a solar heat collection system or a method of providing such systems.

SUMMARY OF INVENTION

According to a first aspect of the invention there is provided a solar water heating system comprising:

-   -   a plurality of lengths of water conduit pipe;     -   a plurality of lengths of water conduit jacket pipe, at least         one of the plurality of lengths of water conduit pipe being         positioned inside each length of water conduit jacket pipe;     -   one or more spacing elements for positioning the plurality of         lengths of water conduit pipe inside the plurality of lengths of         water conduit jacket pipe such that an insulating space is         provided between the lengths of water conduit pipe and lengths         of water conduit jacket pipe; and     -   a plurality of solar collector pipes containing a heat transfer         medium, the solar collector pipes being thermally connected to         at least one of the plurality of lengths of water conduit pipe,     -   wherein the one or more lengths of water conduit pipe are         fluidly connected to form a circulation system.

Preferably, any of the solar collector pipes may be thermally connected to any of the lengths of water conduit pipe.

Preferably, at least one of the plurality of lengths of water conduit pipe is not substantially straight.

Preferably, the system further comprises one or more connection devices for fluidly connecting two or more lengths of water conduit pipe.

Preferably, at least some of the plurality of solar collector pipes form a solar collector.

Preferably, the plurality of solar collector pipes are fluidly connected to the plurality of lengths of water conduit pipe.

Preferably, the solar collector pipes comprise a heat transfer medium pipe contained within an at least partially evacuated tube.

Preferably, the heat transfer medium is water.

Preferably, the system further comprises an insulating material positioned between one or more of the lengths of water conduit jacket pipe and one or more of the lengths of water conduit pipe.

Preferably, the spaces between the plurality of lengths of water conduit jacket pipe and the plurality of lengths of water conduit pipe are fluidly connected.

Preferably, the plurality of lengths of water conduit pipe are positioned substantially co-axially inside the plurality of lengths of water conduit jacket pipe.

Preferably, the plurality of lengths of water conduit jacket pipe is flexible.

Preferably, the plurality of lengths of water conduit jacket pipe are corrugated.

Preferably, the plurality of lengths of water conduit jacket pipe is formed of a plastic material such as polyethylene.

Preferably, the plurality of lengths of water conduit pipe is formed of a metal such as copper.

Preferably, the plurality of lengths of water conduit pipe is formed of a plastic material such as polypropylene or polyethylene.

Preferably, at least one of the plurality of lengths of water conduit pipe and/or the plurality of lengths of water conduit jacket pipe is bent through an angle.

Preferably, one or more spacing elements are attached to the interior surface of at least one of the plurality of lengths of water conduit jacket pipe.

Preferably, one or more spacing elements are attached to the exterior surface of at least one of the plurality of lengths of water conduit pipe.

Preferably, water circulates around the system by thermosiphoning.

Preferably, the system further comprises a pump for pumping water around the system.

Preferably, the system further comprises a heat load.

Preferably, the system further comprises a support device for supporting the solar collector tubes.

Preferably, the support device comprises an at least partially transparent protective cover for the solar collector tubes.

According to a second aspect of the invention there is provided a method of manufacturing a solar water heating system including the steps of:

-   -   positioning one or more lengths of water conduit pipe inside one         or more lengths of water conduit jacket pipe;     -   fluidly connecting one of the one or more lengths of water         conduit pipe with the other lengths of water conduit pipe; and     -   thermally connecting one or more solar collector pipes to at         least one of the one or more lengths of water conduit pipe.

Preferably, the method comprises thermally connecting any of the one or more solar collector pipes to any of the one or more lengths of water conduit pipe.

Preferably, the method comprises the further steps of:

-   -   preparing at least one of the one or more lengths of water         conduit pipe in at least one place for receiving a thermal         connection to at least one of the one or more solar collector         pipes;     -   creating at least one hole in at least one of the one or more         lengths of water conduit jacket pipe, each of the at least one         holes corresponding to the one of the at least one places for         receiving a thermal connection, the said steps of preparing and         creating occurring prior to the step of positioning; and     -   wherein the step of positioning the one or more lengths of water         conduit pipe inside the one or more lengths of water conduit         jacket pipe comprises aligning the at least one hole in the one         or more lengths of water conduit jacket pipe with the         corresponding prepared places of the one or more lengths of         water conduit pipe for receiving a thermal connection to at         least one of the one or more solar collector pipes.

Preferably, the one or more solar collector pipes comprise a heat transfer medium pipe contained within an at least partially evacuated tube.

Preferably, the heat transfer medium is water.

Preferably, the method further includes the step of inserting insulating material inside the one or more lengths of water conduit jacket pipe but outside the one or more lengths of water conduit pipe.

Preferably, the method further includes the step of connecting one of the one or more lengths of water conduit jacket pipe with the other lengths of water conduit jacket pipe.

Preferably, the step of connecting comprises connecting by welding, brazing or soldering.

Preferably, the step of connecting comprises connecting by gluing.

Preferably, the one or more lengths of water conduit pipe are positioned substantially co-axially inside the one or more lengths of water conduit jacket pipe.

According to a third aspect of the invention there is provided a kitset for a solar water heating system comprising:

-   -   one or more lengths of water conduit pipe;     -   one or more lengths of water conduit jacket pipe, at least one         of the one or more lengths of water conduit pipe being adapted         to be positioned at least partially inside each length of water         conduit jacket pipe; and     -   one or more spacing elements for positioning the plurality of         water conduit pipes inside the plurality of water conduit jacket         pipes;     -   wherein the one or more lengths of water conduit pipe may be         fluidly connected to each other to form a fluidly connected         circulation system capable of receiving thermal energy from a         solar collector.

According to a fourth aspect of the invention there is provided a modular solar water heating system comprising:

-   -   a plurality of lengths of water conduit pipe, wherein each         length of water conduit pipe is joined to another length of         water conduit pipe such that the lengths of water conduit pipe         are fluidly connected to form a circulation system;     -   a plurality of lengths of water conduit jacket pipe, wherein at         least one of the plurality of lengths of water conduit pipe is         positioned inside each length of water conduit jacket pipe; and     -   a plurality of solar collector tubes, each thermally connected         to one of the plurality of lengths of water conduit pipe,         wherein any of the solar collector tubes may be thermally         connected to any of the plurality of lengths of water conduit         pipes.

According to a fifth aspect of the invention there is provided a solar water heating system comprising:

-   -   one or more lengths of water conduit pipe;     -   one or more lengths of flexible water conduit jacket pipe, at         least one of the one or more lengths of water conduit pipe being         positioned inside each length of water conduit jacket pipe;     -   one or more spacing elements for positioning the one or more         lengths of water conduit pipe inside the one or more lengths of         water conduit jacket pipe such that an insulating space is         provided between the length(s) of water conduit pipe and         length(s) of water conduit jacket pipe; and     -   one or more solar collector pipes, the solar collector pipes         being thermally connected to the one or more lengths of water         conduit pipe,     -   wherein the one or more lengths of water conduit pipe are         fluidly connected to form a circulation system.

Preferably, the one or more lengths of water conduit pipe are flexible.

According to a sixth aspect of the invention there is provided a water conduit piping element for a solar water heating system comprising:

-   -   a length of water conduit pipe inside a substantially coaxial         and coterminous length of water conduit jacket pipe, wherein     -   the conduit pipe is joined to the jacket pipe at both ends by         annular elements and     -   the conduit pipe, the jacket pipe and the annular elements         together enclose a sealed insulating space and     -   the annular elements are capable of joining to like annular         elements to form a fluidly connected water conduit pathway and     -   wherein the annular elements are formed of a material with a         poor or, at most, moderate thermal conductivity.

Preferably, the water conduit piping element further comprises at least one port along its length that facilitates the thermal connection of a solar collector tube to the central water conduit pipe.

Preferably, a port wall spans the radial extent between the water conduit pipe and the jacket pipe so that the conduit pipe, the jacket pipe, the annular elements and the port wall together enclose a sealed insulating space.

Preferably, the water conduit piping element is substantially bendable.

Preferably, the water conduit piping element comprises a substantial bend in the water conduit pipe.

According to a seventh aspect of the invention there is provided a solar heat fence comprising:

-   -   one or more lengths of water conduit pipe;     -   a plurality of solar collector tubes, the solar collector tubes         being thermally connected to the one or more lengths of water         conduit pipe,     -   wherein the one or more lengths of water conduit pipe may be         fluidly connected to each other to form a fluidly connected         circulation system capable of receiving thermal energy from a         solar collector.

Preferably, the system further comprises a heat load.

Preferably, the solar collector tubes are arranged in a substantially vertical fashion.

Preferably, the one or more lengths of water conduit pipe form a fence boundary enclosing an area.

Preferably, the lengths of water conduit pipe connected to the solar collector tubes functioning as the fence are not substantially straight.

BRIEF DESCRIPTION OF THE DRAWINGS

Forms of the invention are described by way of example and with reference to the accompanying drawings, in which:

FIG. 1 is a schematic drawing of an embodiment of a solar heat collection system of the invention,

FIG. 2 is a schematic cross-sectional drawing of a straight joint according to one embodiment of a heat collection system of the invention,

FIG. 2B is a schematic cross-sectional drawing of an elbow joint according to one embodiment of a heat collection system of the invention,

FIG. 2C is a schematic cross-sectional drawing of a straight joint according to another embodiment of a heat collection system of the invention,

FIG. 2D is a schematic cross-sectional drawing of a straight joint according to another embodiment of a heat collection system of the invention,

FIG. 3 is a schematic cross-sectional drawing of a tee joint according to one embodiment of a heat collection system of the invention,

FIG. 4 is a schematic cross-sectional drawing of a straight joint according to another embodiment of a heat collection system of the invention,

FIG. 5 is a schematic cross-sectional drawing of a tee joint according to another embodiment of a heat collection system of the invention,

FIG. 5B is a schematic cross-sectional drawing of a straight joint according to another embodiment of a heat collection system of the invention,

FIG. 5C is a schematic cross-sectional drawing of a straight joint according to another embodiment of a heat collection system of the invention,

FIG. 5D is a schematic cross-sectional drawing of an elbow portion according to another embodiment of a heat collection system of the invention ,

FIGS. 6, 6B, 7, 8, 9 and 9B illustrate alternative embodiments for connection of solar tube heat collecting elements to conduit and jacket pipe of a solar heat collection system of the invention,

FIG. 9C illustrates one aspect of a solar heat collection system according to an alternative embodiment of the invention,

FIG. 10 is an illustration of a portion of solar fence panel according to one embodiment of the invention,

FIG. 11 is an illustration of a support device according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of one embodiment of a solar heat collection system of the invention. The system comprises solar collector tubes 1 as heat collecting elements, which can be arranged in various arrays to suit any particular installation. In this embodiment, the solar collector tubes are evacuated solar tubes, although it will be known to those skilled in the art that alternative forms of solar collector tubes are possible. In the figure three arrays each of a series of solar tubes side by side are shown. Each array may comprise any number of solar tubes of any size. The open ends of the solar tubes of each array are coupled to lengths of jacketed insulated piping 3 to circulate the working fluid as is further described with reference to FIGS. 6 to 9.

A conduit system conducts working fluid such as water between heating elements 1 and from the heating elements 1 part way or full way to a heat load (not shown), and from the heat load back to the heating elements. Each section 4 of the conduit system comprises substantially coterminous lengths of inner conduit pipe and outer jacket pipe. The conduit pipe and outer jacket of each section 4 are substantially concentric in the embodiment shown with an insulating material in between. Some of the adjacent sections of conduit and jacket pipe 4 are directly joined end-to-end to each other. One or more single or multi-part tee, elbow, and reducing connection devices 5, 6, and 7 join other sections of the conduit and jacket pipe, each connection device comprising opposite inner ends for coupling to opposite ends of two sections of conduit pipe and, around the inner ends, outer ends for coupling to opposite ends of two sections of outer jacket around the conduit pipe.

In one embodiment, each connection device 5, 6, and 7 comprises a larger diameter pipe connection fitting matched to the size of the jacket pipe which couples the jacket pipe, and a smaller pipe connection fitting matched to the size of the conduit pipe and which is located within the interior of the larger diameter fitting connecting the jacket pipe. In an alternative form the connection devices may integrate such conduit and jacket pipe fittings.

The conduit system in a preferred form is made up of multiple sections or lengths, each section comprising a length of conduit pipe with a length of conduit jacket pipe around it. The length of conduit jacket pipe may be of approximately similar length to the length of conduit pipe. A “length” means a section or piece of piping and may include straight, substantially straight, bent or elbow sections within the meaning of the term. Connection devices between these separate sections of the conduit system may be straight, elbow or tee connection devices for example. The connection devices are preferably of a form that to couple one such section of the conduit system to a connection device, the end of the conduit pipe and the adjacent and surrounding end of the jacket pipe of the section both insert into the connection device on one side. Another section of the conduit system couples to the connection device on the other side in the same way (and a third section similarly, for a tee connection device). In one embodiment, the connection devices are integrally attached to one or both ends of a length of water conduit pipe, or to one or both ends of a length of water conduit jacket pipe. In an alternative embodiment, the connection devices are separate to the lengths but couplably attachable to them.

Means may be implemented, at least for some lengths of insulated and jacketed pipe, to avoid stresses in the insulated and jacketed pipe due to the relative longitudinal motion of conduit and jacket caused by temperature differences between the two. For example, sliding seals may mechanically isolate the jacketing from the conduit piping. As another example, the jacketing may be corrugated to allow it to bend or to expand or compress longitudinally.

The lengths of water conduit jacket pipe are positioned inside the lengths of water conduit pipe. In one embodiment, more than one length of water conduit pipe may be positioned within each length of water conduit jacket pipe. Such an arrangement is exemplified in FIG. 6B. In a preferred embodiment, the conduit pipe and jacket pipe (herein alternatively referred to as outer jacket) are positioned substantially co-axially, to provide at least an air space around the conduit pipe between the conduit pipe and the jacket pipe as the insulating layer, so that the jacket pipe both armours the conduit pipe against physical damage and defines around the conduit pipe at least an insulating air space. In a preferred form the space between the conduit pipe and jacket contains an insulating material. The jacket pipe then also armours the insulating material against damage and/or provides protection for the insulating material from the external environment, from degradation over time.

The conduit pipe may in some embodiments be formed of a metal such as copper or in other embodiments of a less thermally transmissive material such as polypropylene or polyethylene or other synthetic plastics material for example. The jacket pipe may be formed of a plastics material such as polyethylene for example.

The spacing between the jacket pipe and conduit pipe is maintained by one or more spacing elements positioned in between the exterior of the conduit pipe and interior of the jacket pipe. In one embodiment the spacing elements are attached to the interior surface of the jacket pipe, whilst in another embodiment they are attached to the exterior surface of the conduit pipe. In a yet alternative embodiment, the spacing elements are separate to the conduit pipe and jacket pipe and are inserted in the relevant position. In a still further embodiment, the insulating material forms the spacing elements such that the spacing is maintained through use of the insulating material between the jacket pipe and conduit pipe.

In FIG. 1 the following reference numerals indicate the following elements:

-   1=array of evacuated solar tubes -   2=base support for evacuated solar tubes -   3=straight length of insulated and jacketed pipe with ports for     coupling to evacuated solar tubes -   4=straight length of insulated and jacketed pipe -   5=tee fitting -   6=90 degree elbow fitting -   7=reducing fitting

The sections 4 of combined conduit and jacket pipe may come pre-formed. They may be sold in a range of standard lengths. The compatible insulated and the protectively jacketed pipe fittings 5, 6, and 7 may also come pre-formed such that installations can proceed by doing end-to-end joins of lengths of pipe, either to each other or to a jacketed pipe fitting.

FIGS. 2, 2B and 2C show different embodiments of joints in a solar heating system of the invention. In FIG. 2 the embodiment is a straight joint. In FIG. 2B the embodiment is an elbow joint. In FIG. 2C a further embodiment is provided in which conduit socket fitting 202 comprises a thread whereby the join can be made by screwing the attachment. The thread of the screw engages with element 209. In this embodiment, a seal 208, typically made from EPDM rubber is provided. In this embodiment, two half-cylinders clamp together over the seal 208 and are held in place by a wedge mechanism as illustrated. Other embodiments of joints will be known to those skilled in the art and are included within the scope of the invention; the embodiments of FIGS. 2 and 2B are provided by way of example only. Opposite ends of two sections of the conduit system are connected by a straight socket connection device which is a two part connection device comprising an inner annular part 202 and an outer annular part 205. The two opposite ends of conduit pipe on either side 201 insert into and are connected by the conduit socket fitting 202. The two opposite ends of the jacket pipe on either side insert into and are connected by the jacket socket fitting 204. In FIGS. 2, 2B and 2C the following reference numerals indicate the following elements:

-   201=conduit pipe -   202=conduit socket fitting -   203=jacket pipe -   204=jacket socket fitting -   205=sliding seal for jacket socket fitting -   206=insulation -   207=insulation of joint

In FIG. 2D there is shown a termination joint according to an embodiment of the invention. In this figure there is provided a threaded copper connector 212 for attaching the portion of conduit to another portion of conduit.

FIG. 3 shows an embodiment of a tee joint in a solar heating system of the invention. The three opposite ends of conduit pipes 201 insert into and are connected by the conduit socket fitting 202. The three opposite ends of jacket pipe 303 insert into and are connected by the jacket socket fitting 204. In FIG. 3 the following reference numerals indicate the following elements:

-   301=conduit pipe -   302=conduit tee fitting -   303=jacket pipe -   304=jacket tee fitting -   305=sliding seal for jacket tee fitting -   306=insulation -   307=insulation for joint

FIG. 4 shows lengths of piping and straight joints in an embodiment of the conduit system for use in a solar heating system of the invention. In FIG. 4 the following reference numerals indicate the following elements:

-   401=lengths of jacketed and insulated pipe with the jacket supported     by a sliding seal -   402=end of a length of jacketed and insulated pipe, or of a pipe     fitting, in position to be joined to the adjoining length 1 of pipe -   403=conduit pipe -   404=annular disks of conduit material at ends of pipe and fittings -   405=support for sliding seal -   406=sliding seal with O-ring -   407=jacketing -   408=insulation

In FIG. 4 a flange such as an annular flange (or disk) 404 on the end of section of conduit pipe 403 surrounded by larger diameter jacket pipe 407 extends radially outward to the end of the jacket pipe, thus presenting a flat face that is rigidly attached and oriented with respect to the conduit pipe 403 and that can be held directly while butting it together against the similar face of an adjoining piping element in order to accomplish a sealed join for the fluid conduit pathway. The conduit pipe 403 is comprised of a material with low thermal conductivity in order that the flange at the joint does not form a thermal short between the working fluid and environment outside the jacket pipe. In FIG. 4 the seal 406 allows relative sliding between the jacket pipe 407 and the conduit pipe 403. This avoids stresses in the conduit and jacket pipe due to longitudinal movement due to temperature changes between the two.

FIG. 5 shows an embodiment of a tee joint in a solar heating system of the invention. The ends of the pipe lengths 501 butt directly against the ends of the tee fitting 502 to form the joins. The joining method could be by welding, for example, or by gluing or chemical welding. The joining procedure can be similar to that of FIG. 4. Two of the three such joins have been made and the remaining unjoined length of pipe is shown oriented and placed in proximity to the joining site on the tee fitting 502, ready to be joined. The corrugated form of the jacket pipe 505 allows it to flex transversely and to expand and contract longitudinally. In FIG. 5 the following reference numerals indicate the following elements:

-   501=lengths of jacketed and insulated pipe -   502=tee fitting -   503=conduit pipe -   504=annular disks of conduit material at ends of pipe and fittings -   505=corrugated jacket -   506=jacketing for tee fitting, not corrugated -   507=insulation

FIG. 5B shows an embodiment of a straight joint according to an embodiment of the invention. In FIG. 5B, the connector 509 has a threaded edge for engaging with a connector element 511. Also provided are rubber seals 510 for sealably engaging the connector element.

FIG. 5C illustrates an element according to an embodiment of the invention. Similarly to FIG. 2D there is provided a threaded copper connector 512 for connecting the length of conduit shown with another length or element of the system.

FIG. 5D illustrates an elbow element according to an embodiment of the invention. In the Figure, conduit pipe 503 is contained with jacket 505 and is surrounded by insulation 507. Thus, the invention provides for such pipes containing a bend or other not-substantially straight portion.

FIGS. 6, 6B, 7, 8 and 9 illustrate alternative embodiments for mounting and connecting each of one or more individual solar tubes to the insulated and jacketed pipe. FIGS. 6, 6B and 7 show embodiments in which a heat pipe 607 is used to extract solar heat energy from the open end of each evacuated solar tube 601. A thermal transfer fitting 608 is used between the head of heat pipe 607 and a copper conduit pipe 602. In FIGS. 6 and 6B the following reference numerals indicate the following elements:

-   601=evacuated solar tube -   602=conduit pipe(s) -   603=working fluid -   604=insulation -   605=protective jacket -   606=dust seal between solar tube and jacket -   607=heat pipe -   608=heat transfer fitting -   609=pin for hinged top on heat transfer fitting -   610=retaining latch or clip for hinged top on heat transfer fitting

In the embodiment of FIGS. 6 and 6B, the solar tube 601 comprises an outer cylinder of glass, closed at one end, which encloses a thermally insulating region of at least partial vacuum around a heat pipe 607 that absorbs the solar heat energy and transfers this energy to the open end of the tube. In one embodiment, heat pipe 607 is formed of a heat transfer medium. In a preferred embodiment, heat pipe 607 contains a heat transfer medium. The heat transfer medium may be water, or water at a low pressure such that the normal boiling point of the water is reduced, or another substance such as an aqueous solution or alcohol. As discussed in relation to FIG. 9, in an alternative embodiment, the working fluid can also be the heat transfer medium to convey the solar energy away from the heat pipes.

The heat transfer fitting 608 transfers heat by conduction between the head of the heat pipe 607 and the conduit pipe 602. The heat transfer fitting 608 is made principally of a material with a high thermal conductivity, such as copper. It fits around the head of the heat pipe 607 with good thermal contact. In the preferred form it has a hinged clam-shell form comprising two parts which pivot around pin 609 and clamps closed around the conduit pipe. It includes a latching mechanism such as retaining latch or clip 610 or other retaining means, to hold the fitting closed after installation. The shape of the heat transfer fitting 608 is such that it maintains good thermal contact with the conduit pipe over a surface area that is larger than the contact area between the fitting 608 and the head of the heat pipe 607. The heat transfer fitting 608 is also shaped such that between the contact areas with the heat pipe head and with the conduit pipe, it maximises the rate of heat flow.

In the embodiment of FIG. 6, a single conduit pipe 602 is provided. In the embodiment of FIG. 6B, however, two conduit pipes 602 are provided. In this latter embodiment, heat transfer fitting 608 provides a thermal coupling between the heat pipe 607 and both conduit pipes 602. The working fluid 603 may be generally circulating in the same direction in each of the conduit pipes 602, or in opposite directions. Further embodiments in which more than two conduit pipes are provided are also within the scope of the present invention.

In the embodiment of FIG. 7 the head of the heat pipe 707 penetrates into the conduit pipe 702 and is immersed in the working fluid. The heat pipe 707 is held in place by a retaining latch or clip 709 and fluid seal such as an O-ring 708 around the heat pipe which seals to the aperture in the conduit pipe. In the embodiment of FIG. 7 the following reference numbers indicate the following elements:

-   701=evacuated solar tube -   702=conduit pipe -   703=working fluid -   704=insulation -   705=protective jacket -   706=dust seal -   707=heat pipe -   708=sealing means for heat pipe -   709=retaining latch or clip for heat pipe

FIG. 8 illustrates an embodiment in which the working fluid floods the solar tube 801, with a sealed pathway formed between the conduit pipe 804 and the each evacuated solar tube 801. A fluid seal such as an O-ring 802 seals between the upper end of the solar tube 801 and a saddle fitting 803 around an aperture in the conduit pipe. In FIG. 8 the following reference numerals indicate the following elements:

-   801=evacuated solar tube -   802=O-ring seal -   803=weld-in saddle fitting -   804=conduit pipe -   805=jacket pipe

FIG. 9 shows a variation of the embodiment of FIG. 8, with forced circulation of working fluid through the solar tube 901. Also, in the embodiment of FIG. 9 the jacket pipe 905 is corrugated for the avoidance of thermal stresses and includes ports for the insertion of solar tubes 901 that extend radially from the conduit pipe 904 and through the corrugated jacketing. In FIG. 9 the following reference numerals indicate the following elements:

-   901=evacuated solar tube -   902=O-ring seals -   903=radial pipe joining conduit pipe with jacket -   904=conduit pipe -   905=corrugated jacket pipe -   906=annulus/disk for welded connection/seal -   907=insulation -   908=working fluid -   909=interior conduit pipe guiding flow to circulation tubes in     evacuated solar tubes -   910=circulation tubes -   911=sealing partition for inner conduit pipe -   912=end cap for interior conduit pipe

In FIG. 9B there is shown an embodiment of the invention, wherein two portions of conduit to which solar collector tubes 901 are attached are joined at joint 932. The two portions of conduit each comprise an annular element to enclose the cavity in which insulation material 907 is contained. The two portions of conduit can be joined by a variety of methods including, but not limited to, gluing, butt-welding, welding, brazing or soldering. As will be known the appropriate method of joining may be dependent on the material from which the conduit, conduit jacket and annular element are formed.

In FIG. 9C there is shown an alternative embodiment of the invention. The embodiment illustrates a plastic inner conduit which can be screwed together with another conduit.

In one embodiment of the invention, each length of water conduit pipe is joined to a length of water conduit jacket pipe as a single length of conduit. In this embodiment, the solar water heating system is formed by joining these lengths together. This method allows construction of a solar water heating system on site. Alternatively, the lengths of conduit pipe are positioned inside the lengths of jacket pipe during the construction of the solar water heating system.

In one embodiment, the lengths of conduit pipe and jacket are flexible. It will be understood that the flexibility in the lengths may be transverse (i.e. bendable) and also longitudinal (i.e. stretchable/compressionable). A variety of methods for achieving this are provided and are mentioned elsewhere herein. Non-limiting example are that the lengths can be made of flexible material, or through a flexible construction technique, such as corrugation. In this embodiment, the solar water heating system may be comprised of a small number of lengths of conduit. In one embodiment, a single length of conduit pipe and conduit jacket pipe is used. The single length is attached to the heat load such that a circulatory system is provided and solar collector tubes are connected to the single length at any of a number of points along the length. This embodiment offers significant advantages over previous arrangements because of the flexibility of positioning the length of pipe to fit the installation and because the solar collector tubes can be attached at any point, as discussed further below.

Alternatively, a number of flexible lengths may be used in combination, or a number of flexible lengths may be used with a number of inflexible lengths. The system is not limiting in terms of the configuration and any combination of flexible or inflexible lengths is provided. In addition, in some arrangements, some of the lengths are bent or not substantially straight.

In the embodiment of a single or small number of conduit lengths, the inner conduit pipe is inserted into the outer conduit jacket pipe. Where the inner pipe is made of a flexible material such as plastic the inner pipe is inserted and shaped to fit the installation at a later point. Where the inner pipe is made of a material such as copper, the copper can be heat-shaped as it is inserted into the outer jacket pipe such that it takes the required shape for the installation.

The insulating material is inserted into the space between the inner and outer pipes. In one embodiment, the insulating material is injected into this space at one or a number of points along the length of the piping. In an alternative embodiment, an insulation material injection device is used to achieve the injection of the material and is typically drawn along the length of the piping as insulating material such as insulating foam is expelled from the device.

The solar collector pipes are thermally connected to the lengths of water conduit pipe as discussed herein. In one method, the water conduit pipes are prepared for receiving the solar collector pipes and thus the thermal connection before being positioned in the lengths of jacket pipe. For example, a hole can be drilled in the conduit pipe and an O-ring inserted to provide the seal, such as is shown in FIG. 7. Furthermore, a protruding stub can be created to attach the O-ring or other seal to, the stub being created either using a tee or other branching means along the conduit or by attaching a stub following drilling a hole using, for example, weld-in saddles. In one embodiment of this method, the jacket pipe has holes drilled into it to correspond with the places in the water conduit that have been prepared for receiving the thermal connection. After insertion of the conduit pipe into the jacket pipe, these holes are aligned such that the solar collector pipes may be thermally connected to the conduit pipe by insertion through the jacket pipe.

Alternatively, the water conduit pipes can be prepared to receive the solar collector pipes after they have been positioned inside the jacket pipes. This method requires the drilling of the requisite holes in the jacket pipe and, if appropriate, the conduit pipe following the insertion of the conduit pipe inside the jacket pipe.

In FIG. 10 there is shown an embodiment of the invention as applied to a solar fence. In this embodiment a portion of solar fence 1000 is comprised of an array of solar collector tubes 1001 attached at one end to a flexible corrugated length of water conduit pipe 1002. At their other ends, the solar collector tubes stand on small wheels 1003. This is to enable easy moving of the fence. In an alternative embodiment, the collector tubes stand on the ground or on feet. A variety of configurations are known to those skilled in the art. In addition, the length of water conduit pipe 1002 is enclosed within a length of water conduit jacket pipe 1004. This is attached to one end of a plurality of solar collector tube covers 1005. The solar collector tube covers are made of a transparent material and protect the solar collector from damage. The solar collector tube covers are therefore preferably made of a resistance material such as a transparent plastic. In one embodiment the length of water conduit jacket pipe 1004 is also flexible allowing for the fence to be moved or easily installed to suit any particular setting.

This embodiment may be applied to, for example, heat a swimming pool. The fence provides both a way of converting solar energy into heat for the purposes of heating the swimming pool, but also to fence the swimming pool area—i.e. provide an enclosure around the pool. In a typical arrangement, the solar collector tubes of the solar fence are configured vertically around the pool. However, other arrangements will be known. This embodiment is not limited solely to the application to swimming pools fences, nor just to fences. A building may be surrounded by such a solar fence as a source of heat energy. Alternatively, the fence arrangement may be provided on the roof of a building with the solar collector pipes at the same angle of slope of the roof, or alternatively, at another angle of slope. In a roof with a variety of slopes and angles the fence may be placed in a number of places on the roof such that the sun's energy is utilised at various parts of the day and year.

In such an embodiment, the conduit tubes and solar collector tubes are supported in place by a support device. Such a support device is illustrated in FIG. 11. In the figure, solar collector support device 1100 is comprised of solar collector tube supports 1101 and rings 1104. The rings are attached to the solar collector tube supports 1101 and circle the conduit jacket pipe 1102 to hold the solar collector tube supports 1101 in place with respect to the conduit. Conduit pipe 1103 runs inside conduit jacket pipe 1102. Solar collector tubes 1106 are positioned within the solar collector tube supports 1101 and held substantially in place thereby. There are holes 1105 in the conduit jacket pipe 1102 through which one end of the solar collector tubes pass such that the thermal connection to the conduit pipe 1103 can be made. Also provided are solar collector protectors 1107 to cover the solar collector tubes 1106 and protect them from damage. The protectors 1107 are substantially transparent so the sun's energy can pass through and be absorbed and are removable in case of repairs.

The term “comprising” as used in this specification means “consisting at least in part of”. When interpreting each statement in this specification that includes the term “comprising”, features other than that or those prefaced by the term may also be present. Related terms such as “comprise” and “comprises” are to be interpreted in the same manner.

It will be appreciated that the invention broadly consists in the parts, elements and features described in this specification, and is deemed to include any equivalents known in the art which, if substituted for the described integers, would not materially alter the substance of the invention. 

1-50. (canceled)
 51. A water conduit piping element for a solar water heating system comprising: a length of water conduit pipe inside a substantially coaxial and coterminous length of water conduit jacket pipe, wherein: the conduit pipe is joined to the jacket pipe at both ends by annular elements; the conduit pipe, jacket pipe and the annular elements together at least partially enclose an insulating space; and the annular elements are capable of joining to like annular elements to form a fluidly connected water conduit pathway, and wherein the water conduit piping element further comprises at least one port along its length that facilitates the thermal connection of a solar collector tube to the central water conduit pipe.
 52. A water conduit piping element as claimed in claim 51, wherein at least one port wall spans the radial extent between the water conduit pipe and the jacket pipe so that the conduit pipe, the jacket pipe, the annular elements and the port walls together enclose the insulating space.
 53. A water conduit piping element as claimed in claim 51 further comprising at least one seal positioned around a surface of each port, the at least one seal being adapted to form a fluid seal between the port and a portion of the solar collector tube.
 54. A water conduit piping element as claimed in claim 53, wherein at least one seal forms a fluid seal between the port and a heat transfer medium pipe of the solar collector tube.
 55. A water conduit piping element as claimed in claim 51, wherein the conduit pipe and annular elements are integrally formed.
 56. A water conduit piping element as claimed in claim 51, wherein the conduit pipe, jacket pipe and annular elements are integrally formed.
 57. A water conduit piping element as claimed in claim 51 that is substantially bent and/or substantially bendable.
 58. A water conduit piping element as claimed in claim 51, wherein the water conduit piping element is adapted to receive at least one solar collector tube support.
 59. A water conduit piping element as claimed in claim 51, wherein the water conduit piping element is adapted to reduce stress caused by movement of the conduit pipe relative to the jacket pipe as a result of temperature differences.
 60. A water conduit piping element as claimed in claim 51 further comprising a flow guide adapted to guide water flow from the conduit pipe into the solar collector tube.
 61. A water conduit piping element as claimed in claim 51, wherein the water conduit piping element is capable of being removeably connected in the solar water heating system.
 62. A water conduit piping element as claimed in claim 51, wherein the water conduit piping element is capable of being connected in the solar water heating system such that there is formed a substantially continuous jacket around the water conduit pathway.
 63. A solar water heating system comprising: one or more water conduit piping elements as claimed in claim 51; and a plurality of solar collector tubes containing a heat transfer medium, the solar collector tubes being thermally connected to at least one of the lengths of water conduit pipe of the one or more water conduit piping elements, wherein the one or more water conduit piping elements are fluidly connected to form a circulation system.
 64. A solar water heating system as claimed in claim 63, wherein the plurality of solar collector tubes are arranged to form a fence.
 65. A kitset for a solar water heating system comprising: one or more water conduit piping elements as claimed in claim 51; and one or more jacketed and insulated water conduit elements, the jacketed and insulated water conduit elements comprising: a water conduit element inside a substantially coaxial and coterminous jacket element, wherein: the water conduit element is joined to the jacket element at each end by annular elements; and the water conduit element, jacket element and the annular elements together enclose an insulating space, and wherein at least one of the annular elements of at least one of the jacketed and insulated water conduit elements is capable of joining to an annular element of at least one of the water conduit piping elements such that: there is formed a fluidly connected water conduit pathway; and there is formed a substantially continuous jacket around the water conduit pathway. 